Another huge raft of critical fixes has been pushed out by Microsoft across almost their entire range of products, including client and server side software and the Windows OS itself.

It’s been a while since I’ve seen such a huge variety of security issues in one update including 5 critical vulnerabilities.

If you are running a Microsoft oriented organization you better get your update testing rig on-line and get rolling ASAP.

Microsoft has fixed 26 vulnerabilities in its software products, including several considered critical, the company said on Tuesday in its monthly security patch report.

The security holes, described in five critical and four important bulletins, affect multiple products, including Windows, Internet Explorer, Exchange, SQL Server and Office. In the worst-case scenarios, exploits could give attackers control of affected systems.

There have been “limited, targeted attacks” to try to exploit this security hole, but no public proof-of-concept code has been made available to Microsoft’s knowledge, wrote Microsoft security official Yunsun Wee in a related blog post.

If a user visits a website that contains “specially crafted content” designed to exploit the vulnerability, attackers could execute code remotely on the affected machine. However, users would have to be tricked into visiting such a website. The malicious code can also be sent as an email attachment, but users would need to open the attachment for the attack to work.

Most of them don’t seem to be out in the wild as such, as in they don’t have confirmed publicly available exploits. There have been cases of targeting attacks using these exploits, so they would be very much considered 0-day attacks and are probably being traded or sold in the underground.

The Common Controls exploit would be mitigated against if you had trained your users well on the dangers of opening unknown attachments as it would come in the form of a malicious .rtf file – most likely via e-mail.

Microsoft patched a Windows Common Control bug in April that “made everyone sit up and take notice” due to the broad scope of important products it touched, said Andrew Storms, director of security operations at enterprise security vendor nCircle.

“There is some good news this month: that the attack vector associated with the [Windows Common Control] patch is an RTF (rich text format) file, and the victim has to explicitly open the file to allow the exploit. If you can’t get this patch rolled out or mitigation applied quickly, you should remind users about the dangers of opening attachments from unknown persons,” he said via email.

The second critical bulletin, labeled MS12-052, concerns four issues with IE that aren’t known to be under “active attack.” If successfully exploited, a malicious hacker could execute code on the affected machine with the privileges of the current user. As with the previous hole, users would need to visit a malicious Web page to fall victim to the attack. This vulnerability is rated critical for IE 6, IE 7, IE 8 and IE 9 on Windows clients and moderate for those same IE versions on Windows servers.

The more serious vulnerability, which effects Internet Explorer – allow code execution. But from the research done, it seems like these are not being actively attacked.

It’s critical for all versions of IE, including the current version IE9.